Metropolitan and micropolitan statistical areas are defined as consisting of one or more adjacent counties or county equivalents with at least one urban core area meeting relevant population thresholds, plus adjacent territory that has a high degree of social and economic integration with the core, as measured by commuting ties. A metropolitan statistical area has at least one urban core with a population of at least 50,000. In a micropolitan statistical area, the largest urban core has a population of at least 10,000 but less than 50,000.